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Rains hit hard

Friday morning, the Valley seemed poised to float away, with floods, accidents, downed power lines and sewage spills; but after a soggy start the weekend ended with clear blue skies and sunshine Sunday morning. Expected heavy rainfall over the weekend never materialized in much of the area.

The break in rain was a lucky one, because things were bad enough Friday.

Some of the worst flooding hit the long-problematic intersection of Highways 12 and 121 in Schellville, south of Sonoma. Running water kept the intersection closed all day Friday after the heaviest rainfall of the storm system dropped just under two inches of water on the area overnight. The Schell-Vista fire department responded to three vehicles stuck in the flooding, making its first rescue of a stranded driver at 5:30 a.m. Friday.

Caltrans completed work at the site this summer, dramatically altering the intersection to address traffic safety concerns. The project, budgeted at $2.4 million, reconfigured the angle of the intersection and added a stop light in response to high accident rates. An emergency worker, who was familiar with the intersection’s history, was on the scene Friday and speculated that Caltrans made minimal alterations to the flood control systems in place, and that the work focused almost solely on the traffic pattern.

Flooding appeared to be worse than ever in the area. In the early morning, Broadway was washed out for nearly three-quarters of a mile north of the new traffic light. One landowner, whose family had been on a property adjacent to the intersection for four decades, said the flooding Friday was the worst she had ever seen.

"That was never intended to be any kind of flood control project," said Caltrans spokesperson Robert Haus. "This particular project was purely a traffic-safety improvement project

Rainfall totals varied widely up and down the Valley. According the Gen. Vallejo Home, Sonoma received 3.08 inches of rain from 4 p.m. Thursday night to Monday. Jim Berkland, a retired geologist in Glen Ellen, reported 10 inches of rainfall over the five-day period in his area. In the larger region, some of the heaviest rains came at higher elevations, with the National Weather Service measuring 15.88 inches falling on Venado, which sits west of Healdsburg on Mill Creek Road at 1,260 feet.

All that rain had the Sonoma Creek moving large amounts of water at a furious pace. Richard Dale, of the Sonoma Ecology Center, said that, based on provisional USGS data, Sonoma Creek hit over 10,000 cfs (cubic feet/second) from 5:15 to 5:45 a.m. Dale also took an average of the flow for the entire period from midnight to midnight on Nov. 30, and found that 1.908 billion gallons of water passed the Sonoma Creek gage at Agua Caliente.

“There is growing speculation and an expectation that storms are dropping more water faster as the climate warms,” said Dale in an email. “If that water were slowed down, allowed to move more slowly across the land and to sink in, there would be less flooding and more groundwater and surface water in the dry season. That’s the reason for several projects SEC and others are working on in the Valley – to keep some of the plentiful winter rains around longer into the dry season, and to reduce flooding.”

In addition to overflowing Sonoma Creek and its tributaries, the winds and rains downed trees throughout the Valley and the slick conditions caused at least one accident on the Plaza when an 18-wheeler skidded at the corner of First Street West and Napa Street around 9 a.m. and knocked down a street lamp, exposing live wires.

By the evening, the rain had winnowed down to a consistent drizzle, but the wet weather surely kept some families away from the Plaza for Santa’s annual visit. The turnout looked to be about half the usual number for a soaked Santa’s arrival on atop an antique fire truck.

More rainfall is expected Tuesday night, though it’s not expected to be as heavy as last week’s.

Updated 1:20 p.m. Tuesday, Dec. 4. with quote from Caltrans.